Duplex method of and apparatus for sending telegraphic messages



E. s. SANDBERG AND L. B. :NEWELL. DUPLEX METHOD OF AND APPARATUS FOR SENDING TELEGHAPHIC MESSAGES.

I APPLICATION FILED JULVZI' 1917.

1 $33,452. I Patented Mar. 9, 1920.

3 SHEETS-SHEET /NE/VTORS BY W Mk E. S. SANDBERG AND L. B. NEWELL.

DUPLEX METHOD OF AND APPARATUS FOR SENDING TELEGRAPHIC MESSAGES.

' APPLlCATlQN FILED lULY 21.1912.

1,333,452. I v Patented Mar.9,1920,

3 SHEETS-SHEET 2- Fi i:

I INVENTOR v @2373 M,

ATTORNEY,

E. s. SANDBERG AND L. B. NEWELL.

DUPLEX METHOD OF AND APPARATUS FOR SENDING TELEGRAPHIC MESSAGES. v

I APPLICATION FILED .ULY 21' 1917- 1 ,333 ,452. Patented Mar. 9, 1920.

3 SHEETS-SHEET 3- (f, I Ira/24mm:

W WORM? EUGENE s. saivnnnnc AND aramie s.

ivnwnnn, orsrarivenrnnn, ILLINOIS.

DUPLEX METHOD OF AND APIPARACEUE? FQR SENDING TELEGRAPHIC MESSAGES.

Specification of Letters Patent.

Patented Mar. 9,1920.

Application filed July 21, 1917. Serial No. 181,973.

To all whom it may com-cm:

Be it known that we, EUGENE SIXTEN SANDBERG and LELAND BEEMAN NEWELL, citizens of the United States, residing at the city of Springfield, in the county of Sanga- 111011 and State of Illinois, haveinvented certain new and useful Improvements in DupleX .Methods of and Apparatus for Sending Telegraphic Messages, of which the follow- This invention doubles the capacity of an ordinary single-w re line for Morse telegraphy even over its capacity when operated by a duplex machine such as is now in ordinay use, and reduces the cost of installations at stationsby doing away with the r'el lays and localbatteries at stations, theMorse sounders operating with the main-line current. FVith one single-wire Morse circuit such as is now in common use and the addition of this invention the eflectisobtained of two single-line Morse circuits consisting of two separate complete and independent circuits. As wire is the greatest expense of a telegraph system, this invention is of vital importance, because it enables one'wire to do the work of two. 7 Other economies will hereinafter appear.

Primarily these results aredue to the substitution of alternating current electricity for the direct current now customary in Morse telegra-phy, and the sending of a message 1n one dlrection on the pulsations 1n one direction on a wire of that current and simultaneously another message on the same wire on the pulsations of that current'traveling in the opposite direction. This mode of 7 using the alternating current for the purpose stated is made possible by the dividers which constitute part of this invention and which are hereinafter described.

* It is to beunderstood that the words positive and negative used herein-are relative terms arbitrarily applied like algebraic sym- .bols, and that the current or pulsations, traveling in one direction :and herein termed positive would as well have been denominated negative and vice versa. Merely for the purposes of description the current flowing in one direction is called positive and the opposite negative.

In the accompanying drawings forming part of this specification and in which like numbers of reference denote like parts wherever they occur,

Figure 1 is a diagrammatic view;

I Fig. 2 is a top plan view of a divider cell;

Fig. 3is a side-elevation of such cell; Fig. 4: is a diagrammatic view of the wiring at a station where an incandescent lamp is provided to-be cut in when the sounder is cut out; and 1 f Fig. 5 is a, diagraimnatic view showing separately the wiring atthe said station of the switch, the sounder, andthe incandescent lamp.

- A pair of dividers, 1 and 2 respectively, is located at each station, and each divider is composed of a. cell or jar 3 containing a liquid 4 having certain chemical properties or characteristics, each of thesaid cells hav.

ing, also, a pair of terminals, the metallic plates 5 and 6 of which are at least partially submerged in the said liquid 4;, acting as an electrical conductor therebetween, and which are supported preferably by means of a hook or books 7 engaging the-edge 8 of the jar 3. f f

One of the said metal plates-is composed of one metal or other suitable material, and

. theother of another. Each is provided'with a binding-post 9,to which awire 10 or 11 is connected, which wires 10 and 11 are branch wires from the main or line wire 12. The main line wire 12 branches into two wires at each station, which combine in or lead back to wire 12 in leaving the station, which wire '10 may be termed the positive wire and 11 the negative wire, divider 1 being designated as positive and divider2 negative, and plate 5 denominated positiveand plate 6 negative. Thus the plates 5 and 6, with their resp'ective binding-posts 9, constitute terminals, which by the chemical. action thereon of the liquid 4 act as selective terminals to divide the alternating current into positive andnegative'halves or phases, the positive part consisting of those pulsations of the current that travel in one direction, while those that travel in the opposite direction are herein termed negative. I

One of said plates, as 5, may be of aluminum and the other, as 6, of lead. It will be understood, however, that these metals or materials are mentioned only by way of illustration and not in a. restrictive. sense, as

r i pended claims.

and to this solution may be added a saturated solution of ammonium phosphate in dis tilled water, the same be ng mixed by pour- Jilg both into the ar. V i

i It 1s a matter of experimental knowledge thatcertain metals and materials possess a natural attraction or -=affinity for the pulsations of an alternating electric cin-renttraveling in one direction, while other metals and-materials possess 'a'like attraction or i aflinityforthe current traveling in the opposite direction. Thus, if an alternating current bepassed from the generator in Fig. 1 through the wire 12' that branches into wires 10 and 11, and the positive plate 5 is fat the side of: divider l that is nearer to the generator than the negative plate 6' in divider 1,while'in divider 2 the negativeplate Gris closer to the generatorthan the positive plate 5 in divider 2, th'e pulsations "of *the alternating current that travel in one directionand which we call the positive current select tor-themselves the positive plate 5 terminal as their line of affinity or of leastresistance; and as all other dividers to-the end of the line, a. 9., the right- 40 hand' side of Fig. 1 are similarly set or arranged, so that in one jaror cell 3 out of each pair at astationo'r the like the positive platewill be nearer tl'ian the negative plate to the generator and m the other 1 ar the Y negative plate will be nearerthan the positive plate to the-generator the positive c111- rent-will be in efiect a direct current in one direction on the single wire, while-the neg- .ative current' (consisting of the pulsations in the opposite direction and which select 5 ton-themselves the negative plate 6 finals ."asitheir line ofaffinitycroft-least- -'...-ce)

,will bet-in efiect a direct-current in the direction oppositejto the positive current.

In-this explanation or view, it will be im- 2 derstood:that=the pulsations in either direction have greaterafiinitytor the material ot whichpositive plate 5 is composed than for ftllitt of (plate 6, andfind same first presented to them coming toward the generator along the lefthandside-of Fig. 1, just as the other -pulsations found thenifirst presented going awayf-roni v the generator along the right- 1 hand-sine of Fig: 1.

.rIn thei-present Morsetelegraphy and in our system, the stat-ions are connected in series, but our system'differs in that ea'ch station isprovidedwith a pair of dividers 1 and 2 and a key and sounder wired in conjunction with divider 1 and a separate key and sounder: wired in conjunction with di-.

vider 2 (see the diagram-in Fig. 1). One set of these mstruments operates,and can operate, only by means ofthepositive current for the time being and the other by the negative current for the time being, as hereinbetore described. This enables two operators to use the same wire at the same time, While inordinary Morse telegraph only one operator can transmit a message on. one wire at one time. The reason for our result is that, by dividing the alternating current as-aforesaichthe one wire is in effect split into two wires wherethe'current enters the station.-

Having passed through the dividers and the respective 1nstruments,-the two direct currents or the two halves or phases of the alternating current) pass into the'wire 12 1 again as alternating current.

'When'tho Morse key on. one of the parts of the split wire is open, only a current traveling in' one. direction can pass over the line at any point. When the key on the other part of the split wire is open, only a. current in the other direction can pass When both keys are open, no currents are passing overtheline. {WVhen both keys are 'closechan alternating current passing over theline, but is split into two direct currents at the stations, travelingrin opposite directions It will be seen that two telegraph. operators cantransmit a. messageat the same time, one

. of them using the positive current side, and

the other operator using the negative current side. Bv this arrangement. we have exactly theefi'ect or two-wires under the system'of wiring now -i'n vogue. One'sid, of

the-wire line may be operated as an ordinary line connected to allstations. while simultaneously the other side 1s used as athrough trunk line.

VVhen allthe keyson-the line are closed, and an alternating current 151011 5, intothe wire trom one terminal station 9., the generator in -Fig. 1), the, Morse soundcrs will vibrate so asvto give forth asharp. me-

tallic humming note; the variations in length of which when broken by a key determine Whether the signals are dots or dashes. It

is quite lll'lD'OIifiDb that the armature bar of the sounders be raised considerably above the heads-of the magnet cores-approximately one-eighth inchto avoid sticking of the sounding bar. Toobtainthe best results, the bar should beso adjusted as to leave only the slightest margin ofplay between the sounding contacts. This willgive a sharpsingi-ngtone that is eas l read by gt-telegraph operator.

This system presents the advantage of allowing at willeither two sendings or two receivings without changing the apparatus at any terminal or intermediate station, whereas the present duplex system allows only a sendingand a receiving from each of two terminal stations. 7

By sending and receiving is meant the would not enable one to send a message from the home to a distant station. In the duplex the receiving means is tuned to catch an electric vibration sent from a distant station. The insertion of a key in the receiving means would not enable one to send a signal through these delicately arranged instruments in such manner as to reproduce the signal at the other end.

The advantage of having two sendings or two receivings lies in the fact that all of one relay points messages may have been transmitted, while the other relay point still has several hundred on hand. With our outfit .two men can be placed at the work of sending, while with the present duplex, only one sending is available.

' is not clear.

7 It should be borne in mind that with this system, one man at any station can send to a man at any other station and simultaneously another operator at still another station can send to still another station; that two men cansend from any one station to two men at any other station, or separately to two st tions, or can receivefrom two operators at the same time; or one station can simultaneously send and receive. I

Another advantage of this. system over the present duplex is the fact that the instal-. lation will remain permanent without constant balancing, etc., as is necessary now with the weather changes. This system prothe home terminal. Under the system now generally in use, it becomes necessary for the receiver to require the sender to notify the distant receiverin turn to notify the distant sender of the text of a message that quently, and are more or less numerous according to the abllity of the operators, necessitatlng the delay of the entire wire traffic, in order tostraighten out one receiving These breaks occur fre operator on the clarity of a message. VVit-h our'system, the receiver can notify the distant sender Without delaying the progress of the other two men. This saves ten minutes per hour.

When the use of avrepeater is necessary it is provided in duplicate and with a pair of dividers, like a station.

Our apparatus is a doubly-eflicient field set for the United States A "my Signal Corps, and is simple and practical.

If for any reason the constant humming of the sounder be objectionable, the sounder when not in use can be cut out by asinglelever double-throw knife switch 13 (or any other suitable switch) ,which simultaneously cuts in an incandescent lamp 14, the sounder 15 being shown in Fig. i as within a resonator 16. Whenthe operator desires to take messages, he throws the switch, cutting out thelamp and cutting in the sounder.

When the lamp has been cut in, it will give a steady light except when some operator on the line is calling or otherwise using the wire, when it will flare when the key is opened and closed. Such lamps at stations can be used for calling, by making the signals so slowly that the lamp-flashes can be read as'dots and dashes. After the call has been read by the lamp, the operator can cut 'outthe lamp and receive the message from the sounder by ear. 7

Having thus described this invention, we hereby reserve the benefit of all changes, in form, arrangement, order, or use of parts, as it is evident that man v minor changes may be made therein without departing from the spirit of this invention.

A We claim: p

1. An apparatus for utilizing alternating current electricity in both its phases in telegraphy consisting of an alternating-current generator, a main wire extending from the said generator to a ground terminal, branch conductors from the said main line, a pair of dividers to which said branches lead, means in the said dividers for splitting the said alternating current into its two phases consisting of pulsations in opposite directions, a double set of Morse instruments in the station, means in each divider adapted to conduct the particular phase of the said alternating current received by it through its said branch conductor to its respective Morse instruments, branch conductors leading from the said double set of Morse instruments back to the main line, anincandescent lamp, and a switch so located as to he adaptedto cut out a sounder when not in use and to cut in the lamp at such time and vice versa.

2. -Anapparatus for utilizing alternating current electricity in both its phases in telegraphy conslstlng of an alternating-cur rent generator, a main wlre extending from the said generator to a ground terminal, branch conductors from the said main line at each station, a pair of dividers at each station to which said branches lead, means in the said dividers for splittingthe said al ternating current into its two phases consisting of pulsations in opposite directions, a double set of Morse instruments in each. station, means in each divider adapted to conduct the particular phase of thefsaid al-' ternating current received by it through, its

said branch conductor to its respeetive Morse instruments, branch. conductors at each station leading from the said double set of Morse instruments hack toth'e main line, an incandescent lamp for eachsounder, and a switchv solooated as to be adapted to cut out a sounder when not in'use and to cut in the lamp for each sounder at such time and vice v'ersa.

In testimony our signatures. v

EUGENE S. SANDBERG. LEI-AND B; NEWELL.

whereof We hereunto aflix 

